Gripper bridge for transfer cylinder in rotary printing press having a sheet registering correcting devices

ABSTRACT

In a transfer cylinder of a rotary printing press, a combination of a device for correcting registry of a sheet being printed by deforming the leading edge of the sheet, a gripper bridge including three gripper pad bars disposed end-to-end over the length of the bridge, each of the pad bars being individually adjustable in elevation and having a plurality of grippers associated therewith, and an adjusting member carrying the middle gripper pad bar and the grippers associated therewith and being adjustable along the path of feed of the sheet for deforming the leading edge of the sheet, and means effective during operation of the correcting device for closing all of the grippers associated with the middle gripper pad bar and only the outer endmost grippers of the grippers associated with the outer gripper pad bars, and releasing locking pressure of the remaining grippers associated with the outer gripper pad bars and located between the closed outer endmost grippers thereof and the closed grippers associated with the middle gripper pad bar.

United States Patent Barthel 1 Aug. 8, 1972 [54] GRIPPER BRIDGE FORTRANSFER CYLINDER IN ROTARY PRINTING PRESS HAVING A SHEET REGISTERINGCORRECTING DEVICES [72] Inventor: Karl Barthel, Heidelberg, Germany [73]Assignee: Heedelberger Driic limaschinen Aktiengesellschaft, Heidelberg,Germany [22] Filed: Feb. 20, 1970 [21] Appl. No.:- 13,050

[30] Foreign Application Priority Data Feb. 27, 1969 Germany ..P 19 09795.1

[52] US. Cl. ..271/53 [51] Int. Cl. ..B65h 9/04 [58] Field of Search..271/53, 51, 80, 82; 101/408, 101/409, 410

I [56] References Cited UNITED STATES PATENTS 2,577,099 12/1951 Albrecht..271/53 UX 1,869,403 8/1932 Belluche ..271/53 2,286,032 6/1942 Eckhard..271/53 X Primary Examiner-Jospeh Wegbreit Attorney-Curt M. Avery,Arthur E. Wilfond, Herbert L. Lerner and Daniel J. Tick ABSTRACT In atransfer cylinder of a rotary printing press, a combination of a devicefor correcting registry of a sheet being printed by deforming theleading edge of the sheet, a gripper bridge including three gripper padbars disposed end-to-end over the length of the bridge, each of the padbars being individually adjustable in elevation and having a pluralityof grippers associated therewith, and an adjusting member carrying themiddle gripper pad bar and the grippers associated therewith and beingadjustable along the path of feed of the sheet for deforming the leadingedge of the sheet, and means efiective during operation of thecorrecting device for closing all of the grippers associated with themiddle gripper pad bar and only the outer endmost grippers of thegrippers associated with the outer gripper pad bars, and releasinglocking pressure of the remaining grippers associated with the outergripper pad bars and located between the closed outer endmost grippersthereof and the closed grippers associated with the middle gripper padbar.

2 Claims, 7 Drawing Figures PATENTEDAus 8 I972 SHEET 1 [IF 2 FIG.|

FIG.2

PATENTEDAUG 8 I972 SHEET 2 BF 2 FIG. 4

GRIPPER BRIDGE FOR TRANSFER CYLINDER IN ROTARY PRINTING PRESS HAVING ASHEET REGISTERING CORRECTING DEVICES My invention relates to gripperbridge for transfer cylinder in rotary printing press having a sheetregistering correcting device, and more particularly, wherein theregistry correcting device deforms the leading edge of the sheet eitherin the sheet feeding direction or in directions opposite or transversethereto by means of grippers and gripper abutment surface membersadjustable by mechanical control means.

In rotary printing presses, particularly for multicolor printing, eachsheet experiences a slight change in size at each impression. Thisphenomenon occurs especially for offset machines due to the moisteningprocess associated therewith. The dimension in the changing size isdependent on the one hand upon the quality of the paper being imprintedand, on the other hand, upon the size of the sheet and the amount ofmoistening.

To correct the changing size, the heretofore known control devices areprovided between the printing units of the printing press in gripperbridges of the transfer cylinders thereof, which suitably correct theimprinted zone by deforming the leading edge of the sheet in the sheetfeed direction or in a direction opposite thereto. For relatively largesheet sizes the deformation of the sheet increasing with each impressionor printing can assume such dimensions that the necessary deformation ofthe leading edge of the sheet causes misalignments or loss of registryin the middle region of the sheet. The imprinted sheet, in spite ofcorrective measures in the printing material, becomes visibly worsenedand eventually unusable because the maintenance of alignment or registryin the trailing region of the sheet can only be compensated by alignmenterrors in the leading or forward zone of the sheet even if only slight.

Correcting devices are also heretofore known in multicolor rotaryprinting presses which correct size change occurring in the trailing orrearward part of the sheet by bending the leading edge of the sheetperpendicularly to the direction of feed of the sheet. However, even inthese devices alignment errors occur, after a specific bending of theleading edge of the sheet, in the leading or forward outer region of thesheet because the outer edges of the sheet are drawn inwardly during theregistry correcting operation. This elevational ad-. justment of thegripper abutment surface members for bending the sheet convexly upwardlyor downwardly, when considered with respect to the sheet by the grippersfrom one cylinder to another in the printing press, is limited only to afew tenths of a millimeter because otherwise, when transferring thesheet from one gripper system to another, the leading edge of the sheetwould be torn. Greater changes in size for relatively large sheets canthus not always be effectively prevented by these means alone.

It is accordingly an object of my invention to provide gripper bridgefor transfer cylinder in rotary printing press having a sheetregistering correcting device, which would avoid such possible changesin size of a sheet of specific size to be imprinted one, two or moretimes, without permitting the occurrence of alignment or registrydifferences in the leading or forward region of the sheet, which wouldrender the sheet unusable.

With the foregoing and other object in view, I provide in accordancewith my invention, in a transfer cylinder of a rotary printing press, incombination, a device for correcting registry of a sheet being printedby deforming the leading edge of the sheet, a gripper bridge comprisingthree gripper pad bars disposed end to-end over the length of thebridge, each of the pad bars being individually adjustable in elevationand having a plurality of grippers associated therewith, and anadjusting member carrying the middle gripper pad bar and the grippersassociated therewith and being adjustable along the path of feed of thesheet for deforming the leading edge of the sheet, and means effectiveduring operation of the sheet registry correcting device 5 for closingall of the grippers associated with the middle gripper pad bar and onlythe outer endmost grippers of the grippers associated with the outergripper pad bars, and releasing locking pressure of the remaininggrippers associated with the outer gripper pad bars and located betweenthe closed outer endmost grippers thereof and the closed grippersassociated with the middle gripper pad bar.

With such a device as that of my invention, by preselected elevationaladjustment of the gripper pad bars, the leading edge of each newlytransferred sheet can be easily bent so that a part of the changing sizehas thereby been canceled. Thus, the bending of the leading edge of thesheet never has to assume such dimensions that, due to tearing of theleading edge of the sheet, difficulties will arise in the transfer ofthe sheet from one cylinder to the next one or that misalignments orinaccuracies in registry arise in the vicinity of the leading comers ofthe sheet because the remainder of the size change is balanced out bydeforming the leading edge of the sheet in the travel direction of thesheet with the aid of the adjusting member while the printing press isin operation.

It has been found that this combined sheet correction so advantageouslyaffects size changes of relatively large sheets with the imprintedimpression thereon that the alignment or registry accuracy is maintainedover the entire sheet.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin gripper bridge for transfer cylinder in rotary printing press havinga sheet registering correcting device, it is nevertheless not intendedto be limited to the details shown, since various modifications andstructural changes may be made therein without departing from the spiritof the invention and within the scope and range of equivalents of theclaims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings, in which:

FIG. 1 is a schematic front elevational view of a gripper bridgeaccording to my invention;

FIG. 2 is a schematic plan view of FIG. 1;

FIG. 3 is a plan view of the right hand half of an actual gripper bridgeconstructed in accordance with my invention;

FIGS. 4 and 5 are cross-sectional views of FIG. 3 taken respectivelyalong the lines IV--IV and V-V;

FIG. 6 is a schematic end view of a transfer cylinder in which a gripperbridge is installed according to my invention; and

FIG. 7 is a fragmentary top plan view of FIG. 6 showing a scale foradjusting the gripper bridge.

Referring now to the drawings and first, particularly to FIG. 1 thereof,there is shown schematically in elevational view a gripper bridgeaccording to my invention which includes three gripper pad bars 1, 2 and3 which are adjustable in elevation. As indicated by the doubleheadedarrow 4, elevational adjustment of the gripper pad bars 1, 2 and 3 iseffected by adjusting means not shown in FIG. 1. A sheet having aleading edge 5 represented by a dot-dash line is pressed against thegripper pad bars 1, 2 and 3 by three groups 6, 7 and 8 of grippers. Themiddle gripper pad bar 2 is adjusted to a higher elevation than bothouter bars 1 and 3 on opposite sides thereof. The outer bars 1 and 3 areinclined relative to the horizontal or to the non-illustrated axis ofthe transfer cylinder of a printing press on which the gripper bridge ofmy invention is installed, so that the leading edge 5 of the sheet isgiven a slightly convex shape upwardly. If no correction of sheetalignment or registry is necessary, the gripper pad bars 1 to 3 areadjusted so that they are parallel to one another in elevation. Theadjustment in elevation of the gripper pad bars 1 to 3 is always carriedout when the printing press is inoperative.

From the schematic view of the gripper bridge in FIG. 2, it can beobserved that both outer gripper pad bars 1 and 3, as seen in sheet feeddirection, i.e. vertically downward in FIG. 2, are rigidly mounted,whereas the middle gripper pad bar 2 together with the grippers 6 areadjustable in the sheet feed direction, as indicated by thedouble-headed arrow 9. The leading edge 5 of the sheet in the adjustedposition thereof, shown in FIG. 2 is held by the middle grippers 6 andthe respective outermost grippers 8, whereas the grippers 7, shown inphantom, i.e. in dot-dash lines, have been raised from their respectivepad bars 1 and 3 or at least have been freed of terminal lockingpressure. The leading edge 5 of the sheet is thereby induced to followfreely the adjusting movement of the middle gripper pad bar 2 and therespective grippers 6, which are kept closed. Distortions in the leadingedge 5 of the sheet, which would otherwise occur if all the gripperswere kept closed during the alignment correction operation, are therebyavoided.

FIGS. 3 to 5 show the structure of a gripper bridge according to myinvention in detail. A transfer cylinder 10 (FIGS. 4 to 6) of a printingpress, such as a multicolor rotary printing machine, is formed with aflattened portion 11, corresponding to a secant intersecting theperiphery of the transfer cylinder 10. The flattened portion 11 providesa base for mounting the gripper bridge of my invention thereon by meansof a pair of brackets 12 and 13 which are screwed to the flattenedportion 11 and carry all of the parts of the gripper bridge. In FIG. 3,only the right-hand half of the gripper bridge of my invention isillustrated, the non-illustrated left-hand half thereof being merely amirrorimage of the illustrated half and consequently being omitted fromthe drawing. The gripper pad bar 3 is mounted on the bracket 12 so thatit is adjustable in vertical direction. The elevational adjustment isprovided by two set screws 14 having respective threaded portions 35screwed into internally threaded bores 38 of the bracket 12. The setscrews 14 are located respectively at each end of the gripper pad bar 3.The elevational adjustment is effected after tension screws 15 have beenloosened. By tightening these tension screws 15, the gripper pad bar 3is rigidly connected to the bracket 12.

The grippers 7 and 8 cooperate with the gripper pad bar 3. They areloosely rotatably mounted on a gripper shaft 16. Through a compressionspring 17, they are braced against an entrainer member 18 having anentrainer portion 19 formed with a bore through which a stop screw 20extends. The stop screw 20 has a free end 21 which is adjustablerelative to an abutment surface 22 of the grippers 7 and 8,respectively. In two bearings 23 and 24 of the bracket 12, there ismounted an adjusting shaft 25 having a free end projecting out of thebearing 23. A roller lever 26 is secured to the free end of theadjusting shaft 25 and carries a cam roller or follower 27. A journal ofthe adjusting shaft 25 projecting through the bearing 24 is rigidlyconnected to an adjusting member 29 by means of a pin 28.

The shape of the adjusting member 29 is more clearly apparent from FIG.5. The adjusting member 29 is pivotable about the axis 30 of theadjusting shaft 25. The basic attitude or position of the adjustingmember 29 is provided by an adjusting screw 31 which is threadedlyreceived in a threaded bore 32 formed in the flat portion 11 of thetransfer cylinder 10. Helical springs 33, located between the adjustingmember 29 and the flat portion 11 of the cylinder 10, bias the adjustingmember 29 clockwise, as viewed in FIG. 5, toward the adjusting screw 31.The adjusting member 29 is pivotally mounted on a pin 34 (FIG. 3) at aside of the adjusting member 29 facing away from the adjusting shaft 25.

The gripper pad bar 2 is provided at the adjusting member 29. The rail 2is adjustable in elevation by means of the set or adjusting screws 36after the tension screws 37 have been loosened. Both grippers 6 areloosely mounted on a hollow shaft 39, coaxially through which thegripper shaft 16 extends. The inner diameter of the hollow shaft 39 andthe outer diameter of the gripper shaft 16 differ at least by about 2mm. On the hollow shaft 39, between both grippers 6, a double entrainermember 40 having two similar entrainer parts 41 is secured. In bothentrainer parts 41, stop screws 20 are threaded, which press against theabutment surfaces 22 of the gripper 6 when the grippers 6 are raised.Both grippers 6 are continuously biased by a respective compressionspring 17 clockwise in direction toward the gripper pad bar 2. Thus, allof the grippers are individually sprung.

The disposition of the adjusting member 29 and the components locatedthereon in the transfer cylinder 10 is especially apparent from FIG. 6.In particular, one can determine from FIG. 6, the control means fortuming the adjusting shaft 25, and thus the manner in which theadjusting member 29 is pivoted about the pivot axis thereof forcorrective purposes.

The aforementioned cam roller of follower 27 engages a cam surface path43 of a cam lever 44 for each rotation of the transfer cylinder 10during the corrective action and thereafter until the sheet is removedfrom the cylinder 10. This cam lever 44 is mounted so as to beadjustably pivotable about a pin 46 in the frame wall 45 of a rotaryprinting press such as of the multicolor type. The free end of the camlever 44 is articulatingly connected to an adjusting device 47 which isalso mounted in the frame wall 45. The adjusting device 47 includes anadjusting screw 48 which extends out of a scale 49, as is evident, inparticular, from FIG. 7. With the aid of an indicator 50 mounted at theadjusting screw 48, a reading can be obtained on the scale 49 of thedistance the leading edge 5 of the sheet is drawn in the direction ofsheet travel or feed or in opposite direction thereto for correctivepurposes. Turning of the adjusting screw 48 effects a lower or higherpositioning of the cam lever 44.

Besides the control components for the adjusting member 29, FIG. 6 alsoshows the control means for the middle grippers 6 mounted on theadjusting member 29. At one end wall of the cylinder 10, a roller lever51 carrying a cam roller or follower 52, is provided, and cooperateswith a cam surface path located in the frame wall 45. The roller lever51 transmits the pivoting movement thereof through a shaft 53 and acontrol linkage 54 to the hollow shaft 39. The pivot bearing 55 of thecontrol linkage 54 that is directly connected to the hollow shaft 39 isdisposed so that the rotary axis thereof is coincident with the pivotaxis 30 of the adjusting member 29, whereby the position of the grippers6 with respect to the gripper pad bar 2 thereof remains unaffected whenthe adjusting member 29 pivots during the corrective action.

The operation of the aforedescribed gripper bridge of my invention is asfollows.

In order to bend the leading edge of a sheet upwardly convex so thatpart of the fanning-out thereof, caused by moisture absorption andfulling of the paper, is compensated for, the tension screws 37 of theadjusting member 29, are loosened and the gripper pad bar 2 is raised bymeans of the adjusting or set screws 36. After the adjustment is made,the tension screws 37 are again tightened. Such an adjustment inelevation is always only of an order of magnitude of fractions of amillimeter. To prevent damage of the sheet due to the varyingelevational adjustment of the gripper pad bars 1, 2 and 3, the tensionscrews for the gripper pad bars 1 and 3 must be loosened, and theadjusting screws 14 must be suitably actuated so that the farthestinwardly located abutment surfaces of the gripper pad bars 1 and 3 arelocated nearly at the same elevation as that of the gripper pad bar 2.The gripper pad bars 1 and 3 thus are disposed slightly inclined to thelongitudinal axis of the transfer cylinder 10. This basic adjustedorientation of the gripper pad bars of a gripper bridge remains constantduring the printing of one typeface or edition. It is effected whilemaking ready the printing work when the printing press is shut down and,the extent of inclination of the outer gripper pad bars 1 and 3 to themiddle bar 2 is so chosen that no misalignment of sheet-to-type occursin the comer region of the leading edge of the sheet in spite of theupwardly convex bend formed in the sheet.

If there should then occur, however, a specific fanning-out of the sheetin a trailing portion thereof so that, for example, the third or fourthprinting is not in alignment with the first two printings, the cam lever44 can be additionally adjusted through the adjusting device 47 so that,after the sheet is gripped, the adjusting shaft 25 is slightly turned bymeans of the cam roller or follower 27 and the roller lever 26 for eachrotation of the transfer cylinder 10, whereby the adjusting member 29,shown in FIG. 5, is pivoted counterclockwise about the axis 30 and in adirection opposing the pressure exerted by the helical spring 33. Thepivoting motion of the adjusting member 29 causes, for example, apulling of the leading edge of the sheet, in the middle region thereon,as is apparent in FIG. 2. But before the leading edge of the sheet, inthe middle region thereof, is drawn or pulled in the sheet traveldirection due to the pivoting of the adjusting member, a slight rotationof the gripper shaft 16 releases the locking pressure from all thegrippers 7 on both sides of the middle grippers 6 or, in fact, actuallylifts the grippers 7 from the sheet.

The outer grippers 8 of the gripper bridge continue to hold the outerends of the sheet 5 firmly, however. This different operation of thegrippers 7 and 8, respectively, located on one and the same grippershaft 16, permits the varying adjustment of the stop screws 20 relativeto the abutment surfaces 22 of the grippers 7 and 8, respectively and,in fact, the spacing between the points of the stop screws 20 and theabutment surfaces 22 for the grippers 7 is smaller than for the grippers8. Consequently, when the gripper shaft 16 is rotated counterclockwise,the grippers 7 are entrained sooner than the grippers 8.

The adjusting member 29 is pivoted only so slightly that the sheet isdrawn or pulled only fractions of a millimeter, at the middle region ofthe leading edge thereof, in the sheet feeding direction. Thedeformation of the leading edge of the sheet is so minimal that nodifferences in alignment occur in the forward or leading sheet areas.The position to which the adjusting member 29 has been pivoted, ismaintained during the rotation of the cylinder 10 until the braced sheethas been transferred to the respective gripper unit. This control of themiddle gripper group 6 is carried out during operation of the printingmachine and, moreover, at each transfer cylinder between the individualprinting mechanisms of multicolor printing presses, for exampie.

The combination of elevational adjustment of the gripper pad bars 1, 2and 3 with control of the middle. gripper group 6, after releasing thelocking pressure of both gripper groups 7, permits a deformation of theleading edge of the sheet which assures printing alignment accuracy overthe entire sheet.

I claim:

1. In a transfer cylinder of a rotary printing press, in combination, adevice for correcting registry of a sheet being printed by deforming theleading edge of the sheet, a gripper bridge comprising three gripper padbars disposed end-to-end over the length of the bridge, each of saidbars being individually adjustable in elevation alternatively parallelto and inclined with respect to the axis of the transfer cylinder andhaving a plurality of grippers associated therewith, and an adjustingmember carrying the middle gripper pad bar and the grippers associatedtherewith and being adjustable along the path of feed of the sheet fordeforming the leading edge of the sheet, and means effective duringoperation of said sheet registry correcting device for closing all ofthe grippers associated with said middle gripper pad bar and only theouter endmost grippers of the grippers associated with the outer gripperpad bars,

and releasing locking pressure of the remaining grippers associated withsaid outer gripper pad bars and located between the closed outer endmostgrippers thereof and the closed grippers associated with said middlegripper pad bar.

2. Gripper bridge for a transfer cylinder in a multicolor rotaryprinting press having a device for correcting registry of a sheet beingprinted by deforming the leading edge of the sheet in the feedingdirection of the sheet or in direction opposite or transverse theretowith mechanical control means, the gripper bridge comprising threegripper pad bars disposed end-to-end over the length of the bridge, eachof said pad bars being individually adjustable in elevationalternatively parallel and inclined with respect to the axis of thetransfer cylinder and having a plurality of grippers associatedtherewith, and an adjusting member carrying the middle gripper bar andthe grippers associated therewith and being adjustable along the feedpath of the sheet for deforming the leading edge of the sheet, all ofthe grippers associated with said middle gripper pad bar and only theouter endmost grippers of the grippers associated with the outer gripperpad bars being closable and the locking pressure of the remaininggrippers associated with said outer gripper pad bars and located betweenthe closed outer endmost grippers thereof and the closed grippersassociated with said middle gripper pad bar being releasable duringoperation of the sheet registry correcting device.

1. In a transfer cylinder of a rotary printing press, in combination, adevice for correcting registry of a sheet being printed by deforming theleading edge of the sheet, a gripper bridge comprising three gripper padbars disposed end-to-end over the length of the bridge, each of saidbars being individually adjustable in elevation alternatively parallelto and inclined with respect to the axis of the transfer cylinder andhaving a plurality of grippers associated therewith, and an adjustingmember carrying the middle gripper pad bar and the grippers associatedtherewith and being adjustable along the path of feed of the sheet fordeforming the leading edge of the sheet, and means effective duringoperation of said sheet registry correcting device for closing all ofthe grippers associated with said middle gripper pad bar and only theouter endmost grippers of the grippers associated with the outer gripperpad bars, and releasing locking pressure of the remaining grippersassociated with said outer gripper pad bars and located between theclosed outer endmost grippers thereof and the closed grippers associatedwith said middle gripper pad bar.
 2. Gripper bridge for a transfercylinder in a multicolor rotary printing press having a device forcorrecting registry of a sheet being printed by deforming the leadingedge of the sheet in the feeding direction of the sheet or in directionopposite or transverse thereto with mechanical control means, thegripper bridge comprising three gripper pad bars disposed end-to-endover the length of the bridge, each of said pad bars being individuallyadjustable in elevation alternatively parallel and inclined with respectto the axis of the transfer cylinder and having a plurality of grippersassociated therewith, and an adjusting member carrying the middlegripper bar and the grippers associated therewith and being adjustablealong the feed path of the sheet for deforming the leading edge of thesheet, all of the grippers associated with said middle gripper pad barand only the outer endmost grippers of the grippers associated with theouter gripper pad bars being closable and the locking pressure of theremaining grippers associated with said outer gripper pad bars andlocated between the closed outer endmost grippers thereof and the closedgrippers associated with said middle gripper pad bar being releasableduring operation of the sheet registry correcting device.